Circuit for electron discharge devices



Oct. 25, 1932. 1. R. WElR 1,884,439-

CIRCUIT FOR ELECTRON DISCHARGE DEVICES Filed Nov. 21. 1928 Inventor: Irvin R. Weir;

His Att orney Patented Oct. 25, 1932 UNITED STATES PATENT FFICE I IRVIN R. WEIR, F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK CIRCUIT FOR ELECTRON DISCHARGE DEVICES Application filed November 21, 1928. Serial No. 320,936.

My invention relates to circuits for electron discharge devices and more particularly to circuits for supplying biasing potential to discharge devices.

One of its objects is to provide means whereby a bias voltage source having low current carrying capacity and having low power rating may be utilized to bias the grid,

or grids, of electron discharge devices of rel- I atively high capacity rating. In general it has for its object to reduce the energy requirements of the bias system.

Another object of my invention is to provide means whereby the resistance of the grid circuit to fiow of grid current may be reduced in response to application of potential to the grid causing the flow of grid current. Thus the grid resistance may normally comprise that of a high resistance source having low current carrying capacity. In response to the flow of grid current in the discharge device the grid circuit is altered in such away that it offers considerably smaller resistance to flow of grid current. A further object of the invention is to provide means whereby this alteration may be effected without materially decreasing the load resistance on the bias source.

The novel features which I believe to be characteristic of my invention are set forth with particularity. in the appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof,may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 represents an embodiment of my invention and Fig. 2 represents a modification thereof.

Referring to the drawing I have shown at 1 an'electron discharge device which, for purposes of illustration, is conventionally represented as being connected to amplify high frequency oscillations produced-by a generator 2 and which are supplied to the grid thereof through a transformer 3 and blocking condenser 4E. The amplified oscillations through ground back to the cathode of the l discharge device 1. Direct current potential is impressed upon the resistance 8 by means of two electron discharge devices 9 and 10 which are connected in a well known manner to rectify the potential supplied thereto by a low frequency source 11. Condenser 12 is connected in shunt with the bias resistance 8 and is utilized for the purpose of smoothing the rectified potential.

In order that the bias system including the source 11 and the rectifying devices 9 and 10 may be of as low capacity as possible, it is desirable that the load resistance 8 be of comparatively high value such that it constitutes a comparatively small load upon the recti-Y fying unit. As ordinarily employed, howtial is supplied thereto, as when the telegraphic key 13 is closed. \Vhen the device 1 is of large capacity, or is comprised of a plurality of parallel connected electron discharge devices, this grid currentmay be of considerable value, such that the resistance 8 must be comprised of a fairly large conductor having necessarily low resistance. Hence, in order to obtain the necessary biasing potential across this resistance, the rectifying unit must be of fairly large capacity.

To obviate this difficulty in accordance with my invention, a second electron dis charge device 14 and an auxiliary resistance 15 of comparatively low valueare employed.

The cathode of this discharge device is connected to the grid of the device 1, and the anode thereof is connected through resistance 15 to the opposite side of the source of biasing potential. Resistance 7 is connected between the grid and cathode of the device 14. By means of a source of potential 16 connected in the grid circuit of the device 14 this grid is normally biased negatively to a value such that the impedance between the cathode and anode of the device 14 is of very high value.

It will be understood that the potential n the resistance 8 is normally such as to establish the proper negative bias upon the amplifier 1. When the key 13 is open and no big frequency potentialis' supplied to the rid of the device 1 little or no grid current ows in that device because of the negative bias. When this key is closed, however, and

high frequency potential is supplied to the 1d of the device 1, a unidirectional current flow in the grid circuit of this device and hence through the resistances 7 and 8 to the cathode. This current flowing through the resistance 7 will overcome the biasing potential 16 and cause the grid of device 14 to assume a positive potential. As such the impedance between the cathode and anode of device 14 is materially reduced and the grid current of device 1 will then flow through the space between the cathode and anode of device 14 and resistance 15 to ground. At the same time while the resistance between cathode and anode is materially reduced to the flow of grid current in the device 1, due to resistances 7 and 15 the load resistance on the rectifier unit will not be materially afi'ected. Thus with this arrangement the resistance 8 may be of very high value and of low current carrying capacity and hence the necessary biasing potential may be secured by means of a power supply unit of relatively low capacity.

With arrangements of this kind it has been found that several electron discharge devices 1 of equal rating connected in multiple may be supplied with biasing potential from a source having about the same rating as is required to supply the biasing potential to a, single one of said discharge devices. It has also been found that the bias source for the grid of device 14 may comprise a storage battery of ordinary construction and that this battery in a circuit arranged as described will continuously retain its charge.

In Fig. 2 I have shown a modification of my invention in which the discharge device 14 is replaced by a mechanical relay having an actuating winding 7 which is connected in the grid circuit in the position occupied by the resistance 7 of Fig. 1, and an armature 1 Thus, when current flows in the grid circuit through the actuating winding 7 the armature 17 is attracted thereby connecting resistance 15' in shunt relation with the source of bias potential. A resistance 18 is inserted in the normal grid circuit between resistance 8 and the armature connection.

' This resistance prevents a material decrease an advantage in the rapidity of operation of the system. Thus, for example, where an electron discharge device 1 is used in high speed telegraphic transmitters the electron discharge device 15 would preferably be employed for the reason that the grid circuit may be altered thereby at the rapid keying speed of the transmitter.

While I have particularly described my invention in connection with a source of biasing potential of a particular type including electron discharge rectifiers it will be understood that it is not limited thereto since it is useful in connection witha bias source of any I type having low current carrying capacity, or high resistance.

While I have shown particular embodiments of my inventi0n,it will of course be understood that I do not wish to be limited thereto since many modifications, both in the circuit arrangement and in the instrumentalities employed, may be made without departing from the spirit and scope of my invention as I intend to cover it in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, an electron discharge device having a grid circuit including a resistance, a source of direct current biasing potential connected in shunt to said resistance, and means responsive to flow of direct current in said source of biasing potential for changing the value of said resistance.

2. In combination, an electron discharge device having a grid circuit including a resistance, a source of unidirectional electromotive force connected in shunt to said resistance, means for impressing high frequency potential upon said grid circuit and means responsive to the flow of direct current in said source of unidirectional electromotive force when said high frequency potential is applied for changing the value of said resistance.

3. In combination, an electron discharge device having a grid circuit including a resistance,'means for impressing potential on said resistance, a shunt path around said resistance, means for impressing high frequency potential upon said grid circuit and means res onsive to said high frequency potential or controlling said shunt path around said resistance.

4. In combination, an electron discharge device having a grid circuit including a said current for controlling said shunt circuit.

5. In combination, an electron discharge device having a grid and cathode, a source of bias voltage connected between said grid and cathode, a resistance connected across said source, a second resistance and means responsive to grid current flowing in said device for effectively connecting said second resistance between said grid and cathode, said second resistance being of small value as compared with said first resistance.

6. In combination, an electron discharge device having a grid cathode, a source of bias voltage for said grid including a source of alternating potential, electron discharge means for rectifying said alternating potential, an impedance of relatively high value connected across the output terminals of said rectifying means, a conductive path around said resistance, a portion of said path having normally high impedance being connected between said grid and cathode, and means responsive to grid current flowing in said discharge device for materially reducing the impedance of said portion of said path, the total impedance of said path remaining of relatively high impedance.

7. In combination, an electron discharge device having a grid and cathode, a source of alternating current, means for rectifying said alternating current, a relatively high resistance load connected across the output of said rectifying means and between said grid and cathode, a relatively high resistance path for grid current connected between said grid and cathode, and means for materially reducing the resistance of said path without materially decreasing the load resistance on said rectifying means.

8. In combination, an electron discharge device having a grid and cathode, a source of biasing potential connected between said grid and cathode having relatively low current carrying capacity, a second electron discharge device connected across said source, and means responsive to grid current flowing in said first discharge device for materially reducing the impedance of said second discharge device to flow of grid current without materially reducing the load resistance on said source.

9. In combination, an electron discharge device having a grid and cathode, a source of biasing potential and a resistance connected in series between said grid and cathode, an electron discharge device having a cathode, an anode and a grid, said cathode being connected through said resistance to one side of said source, the anode being connected to the other side of said source and said grid being connected between said resistance and one side of said source, whereby when current flows in said resistance the impedance between the anode and cathode of said deviceis materially reduced, total impedance of the anode-cathode circuit around said source being such that it continually otters relatively high impedance to current from said source.

10. In combination, an electron discharge device having a grid and cathode, means for supplying high frequency potential to said grid, a source of bias voltage having high resistance, a resistance path connected across said source, I a portion of said path being connected between said grid'and cathode and means responsive to high frequency potential,

on said grid for reducing the resistance of said portion of said path, the total resistance of said path being such that it continuously constitutes a high resistance load on said source.

11. In combination, an electron discharge device having a grid and cathode, a source of biasing potential having high resistance connected between said grid and cathode, a normally high resistance path connected between said grid and cathode and means responsive to direct current flowing between the cathode and grid of said discharge device for reducing the resistance of said path without materially increasing the load on said source.

12. In electrical apparatus for undulatory electrical currents, an electron discharge device having an anode, a cathode and a grid, the series combination of a choke coil and an electron discharge device connected between said grid and said cathode, and a source of unidirectional electromotive force in parallel to the electron discharge device of said series combination.

13. In electrical apparatus for undulatory electrical currents, an electron discharge device having an anode, a cathode and a grid, the series combination of a choke coil, a resistance and an electron discharge device connected between said grid and cathode, and a rectifier producing a unidirectional electromotive force from a source of undulatory electrical energy connected across the electron discharge device in said series combination.

14. In combination, an electron discharge device having a grid and cathode, means for supplying alternating electromotive force to said grid, means for supplying unidirectional electromotive force to said grid, said last means including a path connected between said grid and cathode including means having lower impedance when said alternating electromotive force is supplied to the grid than when said alternating electromotive force is interrupted, and means included in said path to prevent the flow of alternating current therethrough.

15. In combination, an electron discharge device having a grid and cathode, a direct current conductive path connected between said grid and cathode, said path including a source of unidirectional electromotive force, means for supplying alternating electromotivo force to said grid, and means responsive I to said alternating current for establishing a second direct current conductive path in shunt to said first direct current conductive path whereby a substantial portion of the total direct current flowing between said grid and cathode when said alternating electro motive force is supplied flows through said second path.

In witness whereof, I have hereunto set my hand this 20th day of November, 1928.

15 IRVIN R. WEIR. 

